Non-aqueous electrolytic secondary battery

Abstract

A negative electrode comprises a sheet-like negative current collector having a negative electrode mixture layer formed on a surface thereof, and includes a double-side coating, portion in which the negative electrode mixture layer is formed on both sides of the negative current collector, and a single-side coating portion in which the negative electrode mixture layer is formed on one side of the negative current collector. At least a part of the single-side coating portion is disposed at the outermost periphery of the electrode assembly. At least a part of an exposed surface of the negative current collector in the single-side coating portion is in contact with the inner surface of an outer can. The charge expansion ratio of the negative electrode mixture layer in the single-side coating portion is greater than the charge expansion ratio of the negative electrode mixture layer in the double-side coating portion.

1 . A non-aqueous electrolyte secondary battery, comprising:
 a wound electrode assembly in Which a band-shaped positive electrode and a band-shaped negative electrode are wound with a separator interposed therebetween; and   an outer housing can that houses the electrode assembly, wherein   the positive electrode has a positive electrode mixture layer formed on a surface of a sheet-shaped positive electrode current collector,   the negative electrode has a negative electrode mixture layer formed on a surface of a sheet-shaped negative electrode current collector,   the negative electrode mixture layer includes a chargeable and dischargeable negative electrode active material and a binder,   the negative electrode includes a both-surface coated portion in which the negative electrode mixture layer is formed on both surfaces of the negative electrode current collector and a one-surface coated portion in which the negative electrode mixture layer is formed on one surface of the negative electrode current collector,   at least a part of the one-surface coated portion is disposed on an outermost circumference the electrode assembly,   at least a part of an exposed surface of the negative electrode current collector in the one-surface coated portion is contacted with an inner face of the outer housing can, and   a charge expansion coefficient of the negative electrode mixture layer in the one-surface coated portion is larger than a charge expansion coefficient of the negative electrode mixture layer in the both-surface coated portion.   
     
     
         2 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the negative electrode mixture layer includes a silicon material as the negative electrode active material, and a proportion of the silicon material to the negative electrode active material in the one-surface coated portion is larger than a proportion of the silicon material to the negative electrode active material in the both-surface coated portion. 
     
     
         3 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein the negative electrode mixture layer includes a silicon material as the negative electrode active material, and an average particle diameter of the silicon material in the one-surface coated portion is larger than an average particle diameter of the silicon material in the both-surface coated portion. 
     
     
         4 . The non-aqueous electrolyte secondary battery according to  claim 1 , wherein a content of the binder in the one-surface coated portion is lower than a content of the binder in the both-surface coated portion.